But the one that I want to talk about is a big one: 81% of marriages implode, self-destruct, if this problem is present.

And the second reason why I want to talk about it here is because it’s something you can evaluate while you’re dating. Gottman found that the relationships that were the most stable and happy over the longer term were relationships in which the couple shared power. They were influenceable: big decisions, like buying a house, overseas trips, buying a car, having children.

But when Gottman drilled down on this data, what he found was that women were generally pretty influenceable. Guess where the problem lay? Yeah, there’s only two options here, isn’t there? Yeah, we men were to blame.

The other thing that Gottman found is that men who are influenceable also tended to be “outstanding fathers.” So women: How influenceable is your man? Men: you’re with her because you respect her. Make sure that respect plays out in the decision-making process.

Number three, I’m often intrigued by why couples come in to see me after they’ve been married for 30 or 40 years. This is a time when they’re approaching the infirmities and illness of old age. It’s a time when they’re particularly focused on caring for each other. They’ll forgive things that have bugged them for years. They’ll forgive all betrayals, even infidelities, because they’re focused on caring for each other.

So what pulls them apart?

The best word I have for this is reliability, or the lack thereof. Does your partner have your back? It takes two forms.

Firstly, can you rely on your partner to do what they say they’re going to do? Do they follow through?

Secondly, if, for example, you’re out and you’re being verbally attacked by somebody, or you’re suffering from a really disabling illness, does your partner step up and do what needs to be done to leave you feeling cared for and protected?

And here’s the rub: if you’re facing old age, and your partner isn’t doing that for you — in fact, you’re having to do that for them — then in an already-fragile relationship, it can look a bit like you might be better off out of it rather than in it.

So is your partner there for you when it really matters? Not all the time, 80% of the time, but particularly if it’s important to you.

On your side, think carefully before you commit to do something for your partner. It is much better to commit to as much as you can follow through than to commit to more sound-good-in-the-moment and then let them down.

And if it’s really important to your partner, and you commit to it, make sure you move hell and high water to follow through.

Now, these are things that I’m saying you can look for. Don’t worry, these are also things that can be built in existing relationships. I believe that the most important decision that you can make is who you choose as a life partner, who you choose as the other parent of your children.

And of course, romance has to be there. Romance is a grand and beautiful and quirky thing. But we need to add to a romantic, loving heart an informed, thoughtful mind, as we make the most important decision of our life.